Upgrading older version of samba in order to setup PDC

[James Osbourn]

I am currently running version 1.9.18p10 of samba on a solaris machine. 
I have setup encryted passwords and shares and everything is working.  I
would now like to set up the samba box to be the PDC for the pc's.

I have been reading the documentation and the cvs update seems to be the
way to go.  However, I was not the person responsible for installing
Samba.  The person who installed Samba installed it into the /opt
directory rather than the /local directory as is the default today. 
There also were modifications made to the source code before being
compiled and installed.

What I would like to know is whether it is possible to download the
latest samba code and update the code I have in /opt.  Will this effect
and precompile modification that were made to the source code.  If this
is not possible it was suggested that I re-install Samba using the
default location.  Making any modifications to the source code again,
then moving any config data to the new location.  I would rather go with
the former option if it is feasible.

I would be grateful for any help any one can give me.

James Osbourn